IHS: Exam 3: ABG TestRevision Questions And Answers
Verified 100% Correct
Hydrochloric acid (strong acid) pKa is ____.
-7
Carbonic acid (weak acid) pKa is ___.
6
4 most important buffering systems:
1. Bicarbonate buffer (H2CO3/HCO3-)
2. Hemoglobin buffer (HbH/Hb)
3. Protein buffer (PrH/Pr-)
4. Ammonia buffer (NH3/NH4+)
Hydration of CO2 results in:
• carbonic acid
• dissociates into bicarbonate and hydrogen ions
Hydration of CO2 in Carbonic Acid (image)
Five components to the bicarbonate buffer system include:
- Carbon dioxide (CO2)
- Water (H2O)
- Carbonic anhydrase
- Carbonic acid (H2CO3) - Bicarbonate (HCO3 ) carbonic anhydrase (CA) enzyme that catalyzes the
conversion of carbon dioxide and water into carbonic acid bicarbonate buffer system
• CO2 (from aerobic metabolism) slowly combines with water (H2O) to form carbonic acid (H2CO3),
which spontaneously and rapidly deprotonates (H+) to from bicarbonate (HCO3-) -reversible
• CO2 (g)+ H2O(l)↔H2CO3 (aq)↔H+ (aq)+HCO3- (aq)
, Bicarb buffer system base molecule is ___________, and its weak conjugate acid is ________________.
bicarbonate, carbonic acid
• relatively slow reaction accounting for <1% dissolved CO2
Most important buffering system when combined with renal control of bicarbonate and pulmonary
control of CO2:
Bicarbonate buffering system
Hemoglobin Buffering System
• Utilizes histidine to buffer from pH 5.7 – 7.7 (pKa 6.8) • • Second most important buffering system
• Bicarbonate system facilitates movement of CO2 intracellularly.
• Generated protons are bound by hemoglobin
• Hamburger shift
• process reversed in lungs
Hemoglobin Buffering System (image)
Haldane Effect
Deoxygenated hemoglobin has a higher affinity for CO2.
Hamburger Shift/Chloride shift
Bicarbonate anions (HCO3-) are exchanged electroneutrally back into plasma with extracellular chloride
(Cl-)
Chloride shift in lungs:
• Chloride ions move out of RBCs as bicarbonate enters for conversion back to CO2.
• The CO2 is released back into plasma and is eliminate by the lungs
Central chemoreceptors
• lie on the anterolateral surface of the medulla, respond to changes in CSF pH
• CO2 diffuses across the BBB to ↑ CSF H+ ion concentration
-activates chemoreceptors and increases alveolar ventilation
Verified 100% Correct
Hydrochloric acid (strong acid) pKa is ____.
-7
Carbonic acid (weak acid) pKa is ___.
6
4 most important buffering systems:
1. Bicarbonate buffer (H2CO3/HCO3-)
2. Hemoglobin buffer (HbH/Hb)
3. Protein buffer (PrH/Pr-)
4. Ammonia buffer (NH3/NH4+)
Hydration of CO2 results in:
• carbonic acid
• dissociates into bicarbonate and hydrogen ions
Hydration of CO2 in Carbonic Acid (image)
Five components to the bicarbonate buffer system include:
- Carbon dioxide (CO2)
- Water (H2O)
- Carbonic anhydrase
- Carbonic acid (H2CO3) - Bicarbonate (HCO3 ) carbonic anhydrase (CA) enzyme that catalyzes the
conversion of carbon dioxide and water into carbonic acid bicarbonate buffer system
• CO2 (from aerobic metabolism) slowly combines with water (H2O) to form carbonic acid (H2CO3),
which spontaneously and rapidly deprotonates (H+) to from bicarbonate (HCO3-) -reversible
• CO2 (g)+ H2O(l)↔H2CO3 (aq)↔H+ (aq)+HCO3- (aq)
, Bicarb buffer system base molecule is ___________, and its weak conjugate acid is ________________.
bicarbonate, carbonic acid
• relatively slow reaction accounting for <1% dissolved CO2
Most important buffering system when combined with renal control of bicarbonate and pulmonary
control of CO2:
Bicarbonate buffering system
Hemoglobin Buffering System
• Utilizes histidine to buffer from pH 5.7 – 7.7 (pKa 6.8) • • Second most important buffering system
• Bicarbonate system facilitates movement of CO2 intracellularly.
• Generated protons are bound by hemoglobin
• Hamburger shift
• process reversed in lungs
Hemoglobin Buffering System (image)
Haldane Effect
Deoxygenated hemoglobin has a higher affinity for CO2.
Hamburger Shift/Chloride shift
Bicarbonate anions (HCO3-) are exchanged electroneutrally back into plasma with extracellular chloride
(Cl-)
Chloride shift in lungs:
• Chloride ions move out of RBCs as bicarbonate enters for conversion back to CO2.
• The CO2 is released back into plasma and is eliminate by the lungs
Central chemoreceptors
• lie on the anterolateral surface of the medulla, respond to changes in CSF pH
• CO2 diffuses across the BBB to ↑ CSF H+ ion concentration
-activates chemoreceptors and increases alveolar ventilation
